Josephson quantum computing device and integrated circuit using such devices

外国特許コード

F110003358

整理番号

A241-47WO

掲載日

2011年6月23日

出願国

アメリカ合衆国

出願番号

65864705

公報番号

20090261319

公報番号

8284585

出願日

平成17年7月25日(2005.7.25)

公報発行日

平成21年10月22日(2009.10.22)

公報発行日

平成24年10月9日(2012.10.9)

国際出願番号

JP2005013585

国際公開番号

WO2006011451

国際出願日

平成17年7月25日(2005.7.25)

国際公開日

平成18年2月2日(2006.2.2)

優先権データ

特願2004-219284
(2004.7.27)
JP

特願2004-375008
(2004.12.24)
JP

2005WO-JP13585
(2005.7.25)
WO

発明の名称
（英語）

Josephson quantum computing device and integrated circuit using such devices

発明の概要（英語）

(US8284585)A Josephson quantum computing device and an integrated circuit using Josephson quantum computing devices which can realize a NOT gate operation controlled with 2 bits will be provided. The Josephson quantum computing device (1) comprises: a superconducting ring member (10) having a &pgr;-junction (6) and a 0-junction (7); and a quantum state detecting member (20) constituted by a superconducting quantum interference device arranged outside of the superconducting ring member, wherein a bonding and an antibonding state brought about by a tunneling effect between a |↑> and a |↓> state as two states degenerate in energy of the superconducting ring member (10) are regarded as quantum bits. The bonding and antibonding states as the quantum bits are read out by the quantum state detecting member (20). The two bit controlled NOT gate operation can be performed by the two quantum bits comprising said quantum bits.

特許請求の範囲（英語）

[claim1]1. A Josephson quantum computing device, characterized in that it comprises: a superconducting ring member with a pi -junction constituted of a Josephson junction and a first 0-junction or a first and a second 0-junctions each of which is constituted of a Josephson junction; and a quantum state detecting member constituted by a superconducting quantum interference device arranged outside of said superconducting ring member, wherein: a bonding and an antibonding state brought about by a tunneling effect between a | (up arrow) > and a |.down arrow dbl.> state as two states degenerate in energy of said superconducting ring member are regarded as quantum bits, and said bonding and antibonding states as the quantum bits are read out by said quantum state detecting member.[claim2]2. The Josephson quantum computing device as set forth in claim 1, characterized in that said superconducting ring member comprises a pair of semicircular superconductors, a ferromagnetic metal sandwiched between adjacent first ends of said superconductors and an insulator sandwiched between adjacent second ends of said superconductors wherein said two superconductors and said ferromagnetic metal together form said pi -junction and said two superconductors and said insulator together form said 0-junction.[claim3]3. The Josephson quantum computing device as set forth in claim 1, characterized in that said superconducting ring member comprises a first, a second and a third superconductor which as a whole are disposed in the form of a ring and are strips essentially tri-partitioned of the ring and arranged having three interspaces open between their adjacent ends and a ferromagnetic body and a first and a second insulator with which the three interfaces are filled, respectively, wherein: said first superconductor, said first insulator and said third superconductor together form said first 0-junction, said second superconductor, said second insulator and said third superconductor together form said second 0 junction, and said first superconductor, said ferromagnetic body and said second superconductor together form said pi -junction.[claim4]4. A Josephson quantum computing device, characterized in that it comprises: a superconducting ring member having a pi -junction and a 0-junction; and a quantum state detecting member constituted by a superconducting quantum interference device arranged outside of said superconducting ring member, wherein: a bonding and antibonding state brought about by a tunneling effect between a | (up arrow) > and a |.down arrow dbl.> state as two states degenerate in energy of said superconducting ring member are regarded as quantum bits, and said bonding and antibonding states as the quantum bits are read out by said quantum state detecting member.[claim5]5. The Josephson quantum computing device as set forth in claim 4, characterized in that said superconducting ring member comprises a pair of semicircular superconductors, a ferromagnetic metal sandwiched between adjacent first ends of said superconductors and an insulator sandwiched between adjacent second ends of said superconductors wherein said two superconductors and said ferromagnetic metal together form said pi -junction and said two superconductors and said insulator together form said 0-junction.[claim6]6. The Josephson quantum computing device as set forth in claim 4 or claim 5, characterized in that said bonding and antibonding states of said superconducting ring member are controlled by a ratio (gamma ) of Josephson coupling constants at said pi - and 0-junctions.[claim7]7. The Josephson quantum computing device as set forth in claim 4 or claim 5, characterized in that said bonding and antibonding states as the quantum bits are read out by said quantum state detecting member upon applying thereto an external magnetic field.[claim8]8. The Josephson quantum computing device as set forth in claim 4, characterized in that said bonding and antibonding states as the quantum bits are states that are superposed arbitrarily as desired by a microwave with which said quantum bits are irradiated.[claim9]9. An integrated circuit using Josephson quantum computing devices, characterized in that each of said Josephson quantum computing devices comprises: a superconducting ring member having a pi -junction constituted of a Josephson junction and a first 0-junction or a first and a second 0-junction each of which is constituted of a Josephson junction; and a quantum state detecting member constituted by a superconducting quantum interference device arranged outside of said superconducting ring member, wherein: a bonding and an antibonding state brought about by a tunneling effect between a | (up arrow) > and a |.down arrow dbl.> state as two states degenerate in energy of said superconducting ring member are regarded as quantum bits, and said bonding and antibonding states as the quantum bits are read out by said quantum state detecting member.[claim10]10. The integrated circuit using Josephson quantum computing devices as set forth in claim 9, characterized in that said superconducting ring member has a pi -junction constituted of a Josephson junction and a first 0-junction which is constituted of a Josephson junction and comprises a pair of semicircular superconductors, a ferromagnetic metal sandwiched between respective and adjacent first ends of said superconductors and an insulator sandwiched between respective and adjacent second ends of said superconductors wherein said two superconductors and said ferromagnetic metal together form said pi -junction and said two superconductors and said insulator together form said 0-junction.[claim11]11. The integrated circuit using Josephson quantum computing devices as set forth in claim 9, characterized in that: said superconducting ring member has a pi -junction constituted of a Josephson junction and a first and a second 0-junction each of which is constituted of a Josephson junction and comprises a first, a second and a third superconductor which as a whole are disposed in the form of a ring and are strips essentially tri-partitioned of the ring and arranged having three interspaces open between their adjacent ends and a ferromagnetic body and a first and a second insulator with which the three interfaces are filled, respectively, wherein: said first superconductor, said first insulator and said third superconductor together form said first 0-junction, said second superconductor, said second insulator and said third superconductor together form said second 0 junction, and said first superconductor, said ferromagnetic body and said second superconductor together form said pi -junction.[claim12]12. The integrated circuit using Josephson quantum computing devices as set forth in claim 9, characterized in that said bonding and antibonding states of said superconducting ring member are controlled by a ratio (gamma ) of Josephson coupling constants at said first and second 0-junctions and said pi -junction.[claim13]13. The integrated circuit using Josephson quantum computing devices as set forth in claim 9, characterized in that said bonding and antibonding states as the quantum bits are read out by said quantum state detecting member upon applying thereto an external magnetic field.[claim14]14. The integrated circuit using Josephson quantum computing devices as set forth in claim 9, characterized in that two such quantum bits adjacent to each other are so arranged as to bring about a magnetic interaction and operates as a controlled NOT gate.[claim15]15. The integrated circuit using Josephson quantum computing devices as set forth in claim 9, characterized in that said bonding and antibonding states as said quantum bits are states that are superposed as desired by a microwave with which said quantum bits are irradiated to operate as a controlled NOT gate.